Sept 30 (Reuters) - Oil and gas producer Afren Plc said an independent review revealed no further incidents of unauthorised payments so far, two months into a probe that has led to the suspension of four executives so far.

The review began in July after Afren found evidence of “the receipt of unauthorised payments potentially for the benefit of” its chief executive and chief operating officer.

The alleged unauthorised payments are linked to three transactions and the Nigeria-focused company has maintained it did not make the payments.

Afren said on Tuesday that the review, being conducted by British law firm Willkie Farr & Gallagher, is expected to be to be completed by mid-October. It was earlier expected to conclude in September.

“WFG has identified no evidence during the course of the expanded review of further unauthorised payments,” Afren said in a statement.

“The board remains of the view that the assets and operational position of the company have not been negatively affected.”

The company suspended its CEO and COO in July pending the investigation, and in August suspended two associate directors for receiving the unauthorised payments.

Afren’s shares, which have fallen by nearly a third since the review was announced, closed up 1.5 percent at 103.5 pence on Tuesday.

The stock is hovering at a 2-1/2 year low since the review was announced and the company cut its full year production forecast. (Reporting by Abhiram Nandakumar in Bangalore; Editing by Savio D’Souza)